The elasticity of air..another theoretical consideration

Ok, ok, I was just using the subject line term loosely, elastic refers to solid or semi solid states not air/gases which are compressible/expandable to conform to containment. Changes of Volume x Pressure x Temp laws describe those states.

Not all piston speeds are super sonic just the more dramatic, so piston speed slower than speed of sound inside jug throws a pressure/denstiy wave ahead of piston rise, so can puff out a closing valve gap back into the intake.

In jet air craft they compensate for the wing attachment extra area drag by putting a wasp waist in fuselage there, in head ports they do similar in reverse opening up the valve pocket where the guide takes up flow space.

In regards my throat size statements, a similar size single carb/throat, to that used for a one to one devoted carb/throat, can adequately feed a number of cylinders to pretty good power states adequately all by itself. To reach same power as devoted 1:1 throats it takes a bigger single throat but not to the same x-section area as all the mutlti throats added up. I really dove into this a few years ago to find that the stop start pulses of 1:1 needs to be some what larger to feed full rpm than a slightly smaller carb feeding two or more jugs. This was part of the reason ole school Hilborn and similar fuel injection stacks was not considered practical in city traffic. Now a days with electronics they can have the old school look but tamed slow speed behavior. Searched up last few pm's single vs mutli carbs to find most everyone short of top fueler dragster prefer the single over the dual or more carbs. I was looking for solutions to Ms Peel space limitations to find the various EI kits and sizing for ultra lights and carts and snow mobiles. Varying low speed operation was the buggaboo in all of them, so I gave up and going caveman tech, a flattened nail in open fuel pipe in front of 40 mm hole in front of impeller. Methanol may be sprayed in front of impeller to increase the impeller efficiency and mixture compression density/energy content for extra kix.

I've had differing 3 engines, a 2 stroke a V8 and a Combat, that really woke up, able to over rev under max loads of water or wind by doing nothing more but experimenting with tripping up the air flow into head by restriction or creating a pressure wave ahead of carb intake.

There is a blast polished thumb sized area i see on medial surfaces of our head chambers - just crying for a ruffling ramp or groove or dimples experimenter.

Here's Hilborn article that half way applies to this old subject.
http://www.hilborninjection.com/tech_el ... _paper.asp

probably off this subject a little, but,,,

Some years ago I went to an Aircraft museum and got talking to an old fellow about the engines on display.

He was telling about his days towards the end of WW2 as a test pilot on an Australian aircraft, I can't remember the type, but it was a dive bomber of some sort.

The problem they had was when in a dive the engine would over rev and blow, causing a lot of crashes.
His job was to find out why and solve the cause.
From accounts of pilots that survived, they would go into a dive, the engine would over rev and they would close the throttle.
He found that if "he" went into a dive and the engine would over rev, instead of closing the throttle, he opened it fully, the engine went to its max revs as it had something to compress and didn't over rev and destroy itself.

Brave man!

Problem solved.

graeme

DIDNT KNOW what they were doing . ! Please explain the Peugoet 1912 4 valve twin cam , Eh Wot . :shock:

incidently , over 500 mph is the ' Transonic ' range . any material in proximity can induce localised flows OVER
the speed of sound ( my god , how can they survive , theyll blow apart etc & so on . :shock: )

Didnt Know etc . " Maximums gigantic bi-plane of 1894 was powered by two of these amazingly advanced steam engines ,
Which ( ignoring the boiler ) had a weight / power ratio of only 0.78 kg (1.72 lb )/ hp ! Equally remarkably ,
nothing exploded " te he . EXTERNAL Combustion Engine , tecnically .

It is my view that DISPLACEMENT regulations have led ' high speed combustion engines ' up the garden path .
WEIGHT , as a regulation would have allowed large displacement fuel efficent types to evolve , provideing a
good deal greater time period for the combustion process to occur .

If the valve timing were sufficently conservative , only half of the chambers potential being utilised , via sequential injection , it would , with the timing of the occurances sufficently evolved , have the maximum pressure occur at the area of rotation about the connecting rod being tangental to the crankshaft , tereby optimiseing the use of the fuel / air .

Therefore a 5 in bore and a 6 in stroke would be a usefull size with revolutions approaching 4.000 , though as the overall
pressures would not be excessive , these revolutions could easily be exceeded .

Something like the 20 litre four cylinder veteran Grand Prix cars , Fitted with electronic fuel injection , and multi spark ignition, with variable cam timing , for transportation of the masses .

A Bristol Centaurus Cylinder gives about 4 litres capacity , and should be suitable for a motorcyle , with a secondary con rod to a 90 degree piston counter weight should have perfect primary balance .or we could fit a second cylinder . :idea: :shock:

I think in any age any generation knows about as much about what they are doing as any other .
or explain M&M , the Spice Girls . Royalty !
The lowest C.D. of any vehical produced was a pre war thing with a Airfoil Plan section , Square side view cabin , sat on a flat chassis with ( narrow ) wood spoke wheels . about 0.27 for a Production Car .

And if you dont know what yore doing , theres one way to find out .
Hawkers instructed their test pilots to dive steeply from maximum
Altitude at maximum power settings, to find out why the tails feel off the early Typhoon / Napier Sabre H 24 . 500 mph +

Would that be Merlin and one of the Knights of the Round Table?

A Napier Sabre and one of the aforesaid Knights of the Round Table...

Matt Spencer said:

DIDNT KNOW what they were doing . ! Please explain the Peugoet 1912 4 valve twin cam

Click to expand...

Who said they didn't know what they were doing.
Research on everything and anything was proceeding apace.
And there were some mighty machines along the way.
It was said that every engine configuration and development known to man had been tried and tested pre WW1.

However, one of the folks responsible for a little ohc JAP 250cc race engine of the 1920s commented, in the 1950s, that it had been noticed that larger inlet valves was the secret to big power, the easy way, so in the light of this they turned the cylinder head around on an old engine, so the inlet valve was the larger. Engine produced prodigious amounts of power, and revved to beyond 8000 rpm. "With this, we could have conquered the world". Easy, when you know how....

P.S. At 5,500 hp the Napier Sabre was one of the mightiest of the flying machines.
A 24 cylinder sleeve valve engine - keep the mechanics on their toes "where does this go ?".

I read somewhere that the Manx Norton was the first normally aspirated motor to over fill.

Cash

cash said:

I read somewhere that the Manx Norton was the first normally aspirated motor to over fill.
Cash

Click to expand...

I've read that too.
And while I'm sure it has some claim to that, at some revs and with some setups, things like KTT Velocettes and AJS R7s and 7Rs and Excelsior Manxmans etc etc etc , which had similar setups and gave similar outputs and speeds could equally have some claim to that title.

And as Matt pointed out, there were whole generations of race motors pre WW1 that were pretty capable too, and Indian and Excelsior and Harley 8 valve and cammer dirt track motors of the teens. Since they could lap a 1/2 dirt or timber oval at +100 mph, bit of performance there. Harry Ricardo etc had a hand in the design of some of them too.

Hard to measure though - probably depends on how big the spokesmans mouth was....

Air kind of gets into states that could be called liquid plasmas rather that elastic plastic. At this stalled point of posting I offer up Mr. Singh's insights into chamber flame front conditions that over lap with this subject. These groove don't do much, until you operate engine over its prior detonation zone by compression intake &/or ignition time for best pressure hits at best leverage past TDC. Its a deep contraversial subject that takes time and interest following the forums banntering and experimenting. I've tried it on my side valve 18 hp lawnmower to have a roaring torque monster now that keeps its oil a good bit cleaner longer. I don't know how of if these grooves, channels and passageways could be adapted to Norton hemi heads, expect that in Ms Peel, who has squish bands that are ~3/8" wide. Need another subject heading on head swirl turbulence and stagnant regions to stir.

http://somender-singh.com/content/view/7/31/

What sort of era is this sidevalve head, Steve ?

Indian reportedly had some sidevalve head fancy internal shapes for their racebikes in the 1930s - they knew a thing or 2 about winning at Daytona etc. The engines had to be stripped down to be measured, but the heads not shown - so the riders were instructed to sit on them, and no-one saw the details. Whether this was race day hype or for real would be interesting to know.

These ' Over Head Valve ' engines , are Just a Passing Phase . The ' Side Valve ' Will Return . ! :shock:

Atmospheric valves will ultimatly rule again!!! :shock:

Rohan I grabbed that side valve photo off Singh's site but it a basic run of the mill Brigs Stratton or Keohler type vintage air cooled mower engine with cast iron cylinders like ours. These heads have huge piston wide squish surface but a ways from the sparkplug so channels obvious to place. Not so on other heads. Here's view of more modern head grooves. I just don't know if they can work in Peels hemi head with small chambers so will hold off till I see what the carbon deposits reveal. Cleanest surfaces with least carbon deposits are aimmed for.

http://www.herningg.com/projects/groovy ... esults.jpg






http://www.indianchiefmotorcycles.com/oldinjun.htm
The Indian Four began in 1927 when Indian purchased the Ace company. In fact for the first year or so the bike was called the "Indian Ace". (The Ace itself had been developed by the same engineer, one Will Henderson, who had designed the Henderson four. When Henderson was bought out by the Schwinn Excelsior company he left it and in 1919 started the Ace company, building a very similar inline four cylinder engine bike which was bought out by Indian in 1927. The Henderson Four died in 1931 and the Indian Four in 1942. The only engine difference between the early Indian and Ace Fours was that the Indian had five instead of three main bearings. Over the years the sheet metal on the Indian grew more massive. A note on internal combustion engine terminology: Flatheads are also known as L heads or side-valve. (Overhead valves or OHV is actually a misnomer, best term is "valve-in-head".) Prior to 1936 the Four had an F head design (also used in Jeeps a few years later I believe). The exhaust valves were below the head and off to the side as in any old flathead design but the inlet valves were in the head as in later OHV designs. Unique in autmotive history, in 1936 and 1937 only, the F head was reversed. This "upside down" engine is considered a mistake. Everone knows that valve-in-head is much better than the sidevalve design, albeit more expensive to manufacture. The inlet port and valve is much more crucial than the exhaust for breathing and power. The only rationale I can think of is they must have been aiming for cooler exhaust valves as flathead engines, even liquid cooled car ones, are known to overheat especially in the exhaust area, and Indian Chiefs get 10 mph slower top speed as they get hot. Other than the heat issue, for power if you can't have both vales in the head, the F head is the next best choice, and this was reverted to in 1938. At least the Sport model of the 1937 Four had two carburetors. With a Four, the more carbs the better. Most Indian Fours had one carb at the very back to cool the rear cylinder. (Same was used on the Ariel Square Four.) The downside is that the front cylinders get a tiny bit less fuel and air mixture. In 1938 the company did a major redesign of the Four, generally considered a big improvement, but stupidly they did not take the opportunity to go to full OHV (it was still an F head) nor to go to multiple carbs, nor to increase the displacement. Displacement of the Four was always just over 77 CID or 1260 c.c. According to Harry Sucher (in his excellent book "the Iron Redskin") one can bore the Four out to 90 CID (1500 c.c.) and use Sport Scout pistons. One wonders why the factory didn't do this themselves.

hobot quoted an article that said said:

everyone knows that valve-in-head is much better than the sidevalve design, albeit more expensive to manufacture. The inlet port and valve is much more crucial than the exhaust for breathing and power..

Click to expand...

Steve, I would rate that article, even the bit you quoted there, as so full of errors and half-truths that its barely worth considering. Its also modern, so applying 20/20 hindsight doesn't count.
If you want an accurate account of Indian4s and Ace4s, we could dig up something better.
If you want a list of errors, could make a list, if you really really want - pick a bit you want critiqued.

P.S. Over head valve is overheadvalve is ohv, whats he on about ?
Sidevalve motors are still widely used for lawnmowers and pump motors.
Don't bury them just yet.

your not dazzling us with brillance: so i guess trying to baffle us with bull. Throttle has nothing to do with the swept volume of piston stroke. I agree with a previous post u should stick to driving and less bull
Doxford

Dazzle, ha, just posting what I could find on the Indian cycle heads and the controversy of Singh Grooves and what I tried on a side valve that seems to help and not hurt on lugging loads. Not sure what upset ya on the swept area quip? Got to have throttle open to get fullest filling and maybe a funnel down throat to get a bit more. Pointing out my errors improves me so I look forward to that constantly.

I my Peel I'm reducing the effective piston swept area by using a cam that closes intake valve rather late so lowers the dynamic CR, until piston speed builds to hopefully out run detonation as cam ram effect kicks in.

To add/confuse more on this subject line ponders, I've come across references of twins with a carb for each cylinder but connected by a Helmholtz resonator can with small-ish hoses. I've only seen them for sale, for 2 strokes I think but did not find info on how this works or is sized. Our dual carbs come with a small connecting hose but don't know why that is or why some hi end after market duals kits don't employ this hose. The hose size seems too small to make much difference but its so common must be a reason, if someone can enlighten me.